400mm = It gets a bit tricky here, was not always consistent. At f4 I was getting better results with the AF tuning at 0, at f5.6 I was getting better results at -5 AF tuning, a few at -10 but it was not consistent. Might have to also do with shooting technique, at the moment I just have a monopod.

In preparation for next boat race I'm not sure neither which would give best results either the AF-C Single Point or AF-C Dynamic 9. Any preference and recommendation ? Thanks